Entera advances oral challenger to Lilly's Forteo, posting midphase data and heading to pivotal trial

doctor looking at x-ray of spine
Armed with midphase data, Entera plans to start a registration study next year. (Getty/cyano66)

Entera Bio has posted midphase data on its oral challenger to Eli Lilly’s injectable osteoporosis drug Forteo, setting it up to begin a phase 3 registration study of the hormone formulation next year.

Lilly showed injections of human parathyroid hormone (PTH) improved outcomes in postmenopausal women with osteoporosis more than 20 years ago, enabling it to win FDA approval and rack up years of blockbuster sales that are only now being eaten away by off-patent rivals. Entera saw the need to inject Forteo as a barrier to uptake, though, and used its delivery technology to create an oral PTH that recently completed phase 2. 

With Entera previously showing the trial hit its primary endpoint, which looked at changes in a bone formation biomarker at three months, the update focused on secondary bone mineral density (BMD) endpoints at six months. Entera singled out the lumbar spine BMD as the most important secondary objective. The oral PTH achieved a placebo-adjusted increase in lumbar spine BMD of 3.78%.

In a statement, Arthur Santora, M.D., Ph.D., chief medical officer at Entera, noted the “reliable, consistent improvements” and said the oral candidate “performed comparably” to its injectable rival in terms of the effect on lumbar spine BMD. 

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The Forteo phase 3 trial mainly measured bone density of the spine at 12 and 18 months, with only a subgroup being assessed at six months. BMD increased 6.9% in the Forteo subgroup, compared to a less than 1% rise in the six-month placebo cohort. Lumbar spine BMD continued to increase at the 12 and 18 month readouts of the Forteo study, hitting 11.8%, while the placebo group flatlined.   

Armed with the midphase data, Entera plans to start a registration study next year. The study could set Entera up to win FDA approval under the 505 (b)(2) regulatory pathway.